1. Field of the Invention
The present invention relates to a recording method, a recording apparatus, and a recording medium. More particularly, the present invention relates to a recording method for modulating data by a predetermined method and for recording the data, a recording apparatus for use therewith, and a recording medium therefor.
2. Description of the Related Art
Since optical discs such as CDs (Compact Disc) and CD-ROMs (Compact Disc Read Only Memory) can be easily handled and the manufacturing cost thereof is relatively low, these optical discs have been widely used as recording media for storing data. In recent years, CD-R (Compact Disc Recordable) discs that can additionally record data thereon and CD-RW (Compact Disc ReWritable) discs that can record and rewrite data thereon have appeared, and it has become easy to record data on such optical discs. Based on the above, optical discs in compliance with CD standard, such as CD-DA (Compact Disc-Digital Audio) discs, and CD-ROM discs, CD-R discs, CD-RW discs, etc., have become the core for data recording media. Furthermore, recently, audio data compression has been performed by MP3 (MPEG1 Audio Layer-3) or ATRAC3 (Advaptive TRansform Acoustic Coding), and the data is recorded on a CD-ROM disc, a CD-R disc, a CD-RW disc, etc.
However, with the appearance of CD-R discs and CD-RW discs, data recorded on these CD discs has become easy to copy. For this reason, the problem with the copyright protection has occurred, and there is a need to take measures for protecting content data when content data is to be recorded on CD discs.
FIG. 1 schematically shows the disc copying operation. A playback apparatus indicated at reference numeral 41 plays back an original disc, for example, a CD 42. Reference numeral 43 denotes an optical pickup, and reference numeral 44 denotes a playback signal processing section. Data recorded on the CD 42 is read by the optical pickup 43, and the playback signal processing section 44 performs signal processing on the signal output from the optical pickup 43 and outputs playback data. The playback data from the playback apparatus 41 is supplied to a recording processing section 52 of a recording apparatus 51, and an optical pickup 53 records the playback data on an optical disc, for example, a CD-R 54. The data recorded on the original CD 42 is copied onto the CD-R 54. In this manner, by using the playback apparatus 41 and the recording apparatus 51, a copied disc in which the data recorded on the original CD 42 is recorded can be easily created.
In the case of a CD, as shown in FIG. 2, in the playback processing section 44, a frame sync is detected by a sync detection section 46, from a playback signal from an input terminal 45, and EFM (Eight to Fourteenth Modulation) demodulation is performed by an EFM demodulator 47. Furthermore, the EFM-demodulated playback data is supplied to a CIRC (Cross Interleave Reed-Solomon Code) decoder 48, whereby error correction is performed on the EFM-demodulated playback data. In EFM, each symbol (8 data bits) is converted into 14 channel bits, and merge bits of 3 bits are added between two 14 channel bits. A subcode in the playback data is decoded by a subcode decoder 49, and a playback subcode is obtained.
FIG. 3 shows the overall configuration of a recording processing section 52. Data to be recorded is supplied from an input terminal 55 to a CIRC encoder 56, whereby the data undergoes the CIRC coding process. A subcode is supplied from an input terminal 57 to a subcode encoder 58, whereby the subcode is encoded. The output of the CIRC encoder 56 and the output of the subcode encoder 58 are supplied to a multiplexer 60. Furthermore, a frame sync is supplied from an input terminal 59 to the multiplexer 60. The multiplexer 60 causes these pieces of data to be arranged in a predetermined sequence, and the output of the multiplexer 60 is supplied to an EFM modulator 61, whereby the output undergoes an EFM modulation process.
One method for protecting content data recorded on the CD disc is to determine whether the disc is an original CD or is a disc copied from the original CD. For example, in the case of the original CD, copying is permitted, and in the case of a copied disc, further copying can be prohibited.
For the purpose of determining whether the disc is an original disc or a copied disc, a method has been proposed in which a defect is intentionally added in the data when a master is manufactured, and when the original disc is played back, that defect is detected from the data read from the disc in order to determine whether the disc is an original disc. However, this method has the problem in that, in spite of being the original disc, a defect may be contained in the data. Furthermore, depending on the type of defect, there is the problem in that the copying of the data read from the original disc into CD-R discs cannot be prevented.